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S100 Board anomalies

All —

I was playing around, again, with my Z80/8088/PropIO/4MB/PC-AT board set and I still really can’t get it working properly. I have gone over the boards and I’m pretty sure that there aren’t any soldering issues. I’ve also re-flashed the ROMs just in case. Z80 version is 4.8. 8086 version is 10.33a. I will say that I’ve never had a problem with the Z80 board in my old configuration of a legacy 8-bit serial card and CompuPro 64k RAM board.

Here are some of the oddities I’m seeing:
  • When doing a memory map from the Z80, the ROM is shown as all “p” except for the xxFx address which is a “.”. For RAM, it does show “R”. It doesn’t matter where I locate the ROM. So…
D000 R R R R R R R R R R R R R R R R
E000 p p p p p p p p p p p p p p p .
F000 R R R R R R R R R R R R R R R R
  • In the 8086 monitor, if I use the “R” command, it goes into lala land when printing the flags, printing a continuous stream of “0” after half of the flags are printed
  • In the 8086 monitor, if I use the “A” memory map command, I get something that looks like a map, but I get addresses like 00000,00000,80000,C0000 and then each line is a mix of R and p. Finally it goes into lala land at the end, continuously printing spaces.
  • The RTC on the MSDOS board will not store the date/time and it returns garbage when using the monitor commands which read them. I’ve swapped the chip and the battery is installed. As an example time “25:06:00” and date "20<7/26/14”. It appears that the clock isn’t running and can’t be set.
I reduced the system to the PropIO, 4mb RAM and Z80 card so I could test the RAM (at least the first 1mb) using a combination of the N and J commands. It reported bad memory in each segment in the E000-EFFF range. This corresponds to where my monitor resides in the first 64k, so maybe this is expected behavior. No other memory errors were reported. I’d have to say that the first 1MB is probably OK

So that leaves the 8088 or MSDOS boards as being the problem. Since the monitor anomalies occur without the MSDOS board, it has to be a problem with the CPU card.

John, by chance do you have one of the 8086 cards for sale?  Maybe I’ll start from scratch using the 8086 card.

Rich

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Rich Cini
Collector of Classic Computers
Build Master and lead engineer, Altair32 Emulator